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Abstract

The prefrontal cortex (PFC) is thought to play an important role in “higher” brain functions such as personality and emotion that may associated with several gender-related mental disorders. In this study, the gender effects of functional connectivity, cortical lateralization and significantly differences in the PFC were investigated by using resting-state functional optical tomography (fOT) measurement. A total of forty subjects including twenty healthy male and twenty healthy female adults were recruited for this study. In the results, the hemoglobin responses are higher in the male group. Additionally, male group exhibited the stronger connectivity in the PFC regions. In the result of lateralization, leftward dominant was observed in the male group but bilateral dominance in the female group. Finally, the 11 channels of the inferior PFC regions (corresponding to the region of Brodmann area 45) are significant different with spectrum analysis. Our findings suggest that the resting-state fOT method can provide high potential to apply to clinical neuroscience for several gender-related mental disorders diagnosis.

Figures (9)

The fOT channels localization. (Top left) the 3-D image of the optode position; (Bottom) The localizations of all 52 channels were positioned according to the international 10-20 system. Red and blue circles indicate near-infrared light emitter and detector positions, respectively. By using the international 10-20 system the detector 26 was positioned at the FZ marker point while the bottom row of sources 11, 13, 14 and 16 were placed on the T3–FP1–FP2–T4 line. Yellow diamonds indicate the measuring region of PFC.

The flowchart of resting-state fOT data analysis. (a) fOT channels localization above the PFC; (b) distribution of power spectrum within low-frequency band 0.01 to 0.08 Hz of ΔHbO2, ΔHb and ΔtHb for a single channel of one subject; (c) spectrogram from each channel of group-level statistics on averaging that was used for (d) significant difference analysis; (e) distribution of time series within low-frequency band 0.01 to 0.08 Hz of ΔHbO2, ΔHb and ΔtHb for a single channel of one subject that was used for correlation and lateralization analysis; (f) schematic diagram of group average correlation matrices for all channels; (g) schematic diagram of cortical lateralization analysis; (h) schematic diagram of functional connectivity in PFC; (i) schematic diagram of correlation coefficient between left vs. right PFC.

The correlation matrices derived from male and female groups. (a) and (d) are the correlation matrices of each pair channel of ΔHbO2; (b) and (e) are the correlation matrices of each pair channel of ΔHb; (c) and (f) are the correlation matrices of each pair channel of ΔtHb. Each figure shows a 52 × 52 square matrix, where the x and y axes correspond to the channels listed in optode geometry, and where each unit of matrix indicates the mean strength of the functional connectivity between each pair channel.

The distributions of correlation coefficient of male and female group of the same channel. (a), (b), and (c) are the distributions of correlation coefficient of ΔHbO2, ΔHb, and ΔtHb of male and female group of the same channel, respectively. The data were derived from correlation matrices. The red lines mean the result of linear regression. The dots mean the correlation coefficient of male and female group of the same channel.

The functional connectivity pattern of left-side and right-side PFC in resting-state of (a) male group and (b) female group. The red dots represent the channels of each PFC region. The orange lines represent the functional connectivity (group-level correlation network) of left-side and right-side PFC region with correlation coefficient rXY larger than 0.6.

Cortical dominance channel of PFC region by computing LI of all left vs. right channel pairs in resting-state. (a) The result of cortical dominance of male group. (b) The result of cortical dominance of female group. The channels of blue diamond indicate the dominance region of leftward or rightward, and others indicate bilateral dominance.

The spectrogram of ΔtHb of each channel from (a) male and (b) female groups. Color bar indicates the intensity of frequency. The range of frequency 0.01 to 0.08 Hz was used to assess the significantly different channel of PFC between male and female groups. The channels of PFC regions are Ch. 3 to 8; Ch. 13 to 19; Ch. 23 to 30; Ch. 34 to 40 and Ch. 45 to 50 of frequency 0.01 to 0.08 Hz were highlighted on the bottom of figure.

The result of two-sample t-test from power spectrum of each channel of PFC between male and female groups. The Ch. 7, 8, 19, 29, 30, 38, and 39 marked with orange diamonds of left-side PFC and Ch. 13, 23, 34, and 45 marked with orange diamonds of right-side PFC are significantly different with p value < 0.001 between male and female groups.